Rapid rise in toxic load for bees revealed by analysis of pesticide use in Great Britain

Abstract

A strong argument can be made that the European Union has the most rigorous regulatory system for pesticides in the world, and that modern pesticide use poses fewer environmental threats than older regimes. Nevertheless, the impacts of pesticides on bees and other non-target organisms is much debated in Europe as elsewhere. Here we document changing patterns of pesticide use in arable and horticultural crops in Great Britain from 1990 to 2015. The weight of pesticides used has approximately halved over this period, but in contrast the number of applications per field nearly doubled. The total potential kill of honeybees (the total number of LD50 doses applied to the 4.6 million hectares of arable farmland in Great Britain each year) increased six-fold to approximately 3 x 1016 bees, the result of the increasing use of neonicotinoids from 1994 onwards which more than offset the effect of declining organophosphate use. It is important to acknowledge that our simple analysis does not take into account many factors such as differences in persistence, and timing and mode of application of pesticides, that will affect actual exposure of non-target organisms. Nonetheless, all else being equal, these data suggest that the risk posed by pesticides to non-target insects such as bees, other pollinators and natural enemies of pests, has increased considerably in the last 26 years.

Further evidence for a global decline of the entomofauna

“…increasing toxicity trends and spatial coverage of systemic insecticides in Europe and the USA (Meehan and Gratton 2016; Goulson et al . 2018; Douglas et al . 2020), which are hypothesised for having reduced grassland and insectivorous birds in the USA by a respective 4% and 3% annually (Li et al .…”

The insect apocalypse, and why it matters

“…Historically, less intensive farming practices resulted in a patchwork of habitats that were favourable to bees and other insects, including fl ower-rich hay meadows and chalk downland, fallow fi elds rich in weeds, and fl owering hedgerows separating the small fi elds. Modern farming in the developed world is typifi ed by large fi elds maintained as near-perfect monocultures by high inputs of pesticides and fertilizers [15], creating a landscape that is largely inhospitable to wildlife.…”

“…Pesticide use is better documented in the UK than anywhere else, and according to government statistics UK farmers applied an average of 17.4 different pesticides to each hectare of land in 2015, using a total of 16.9 thousand tons of active ingredient (i.e. toxins) [15]. Analysis of the pollen and nectar stores of wild or domesticated bees living in or near either farmland or suburban areas (in the UK and elsewhere) almost inevitably fi nds that their food is contaminated with complex cocktails of insecticides, fungicides and herbicides, usually including neonicotinoids [16][17].…”

Pesticide dosing must be guided by ecological principles

“…Since 1990 the amount (measured in weight) of insecticide applied to farmland in the UK has actually decreased, but this is because modern insecticides are far more toxic than older options 7 . For example, neonicotinoids are 10,000 times more toxic to insects than even DDT 8 !…”